1. Field of the Invention
The present invention relates to a hydrous zirconium oxide dehydration catalyst and a method for producing a compound having a double bond at the terminal position (hereinafter referred to as a "terminal olefin" or ".alpha.-olefin") using such a catalyst.
2. Description of the Prior Art
The present invention relates to a method for producing a terminal olefin. More particularly, the present invention relates to a method for producing the terminal olefin by dehydration of a compound represented by the formula (I) ##STR2## wherein R is a C.sub.2 -C.sub.20 hydrocarbon group which may have one or more double bonds.
It is hitherto well known that an olefin can be produced by dehydration of a compound represented by the formula (I). The details of the method can be taken, for example, from J. Am. Chem. Soc., 85, 2180 (1963), or from Oil Chemistry, 17, 236 (1968). It is also known from DE-A-144 362 and the corresponding CH-A-721077 that zirconium oxide can be used as a catalyst in the dehydration of secondary alcohols. European Patent Specification Publication No. 150,832 also discloses that high purity zirconium oxide, which has a total content of silicon and titanium (expressed as dioxides) of 0.3% by weight or less, is useful as a dehydration catalyst. In addition, European Patent Application Publication No. 0222356 discloses the dehydration of 2-alcohols to terminal olefins using a zirconium oxide catalyst treated with an alkaline solution. Thorium oxide is known as a catalyst for the selective production of the terminal olefin, but its use in industry is difficult because thorium is a radioactive element so that there occurs a serious problem of safety in handling thorium oxide as a catalyst.
Many prior art dehydration catalysts generally suffer from the following disadvantages:
(1) the internal olefin is mainly produced and the selectivity of the terminal olefin is low, especially at high conversion;
(2) the alcohol is converted into a significant amount of ketone (as well as olefin); and/or
(3) the catalyst contains a radioactive element so that there is a problem of safety.
A catalyst has now been discovered which overcomes the drawbacks of the prior art dehydration catalysts by providing high selectivity for .alpha.-olefins while at the same time eliminating the problems attendant with radioactive materials.